OK ... a minor mystery ...
While I've used PICs for many things, I've never made
use of the SLEEP mode. For my 18f2620, the docs state :
"All external interrupts (INT0, INT1 and INT2) can
wake-up the processor from SLEEP, if bit INTxE was
set prior to going into SLEEP. If the global interrupt
enable bit GIE is set, the processor will branch to
the interrupt vector following wake-up."
Well, it doesn't.
I *do* have GIE enabled, and INT1, because the PIC
needs to be awakened by an external device. WDT
timeouts DO happen. The external interrupt DOES work
also, awakening from sleep and calling the ISR just
like it's supposed to.
BUT ... a WDT timeout while sleeping does NOT branch to
the ISR, but instead just picks up the program exactly
where it left off, ie executing the code beyond the
SLEEP instruction. This is OK, convenient even ...
but not what the docs SAY it will do.
The program is writ in MikroPascal, but the actual
SLEEP command is an in-line ASM statement, so MP
ought not be saving the current program counter or
anything else before SLEEP.
Any clues as to why this may be happening ? Mystery
registers that could de-rail the call to the ISR
when interrupts are enabled ? Any info helpful.
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